I believe that Chromium is using Skia's reported font metrics which are currently calculated at https://skia.googlesource.com/skia/+/00dcf668659ab26b8691c64a977fdd19e9e8df09/src/ports/SkFontHost_FreeType.cpp#1411 . The biggest issue is that historically (and as noted above) FT_Face would always use HHEA metrics if they weren't 0, and then fallback to usWin or typo and UseTypoMetrics wasn't looked at to change the priority. As a result Skia has code to look at the UseTypoMetrics bit and if set reads the values from the (FreeType generated) OS/2 table if available instead of using the FT_Face values. So if FreeType interpolates the TT_OS2.sTypo* values in the table it creates for an FT_Face then that should get picked up by any font which sets UseTypoMetrics. Any font which doesn't set UseTypoMetrics will get whatever the FT_Face says to do (except bitmap only fonts use FT_Face.size.metrics values).
I think it would be great for FreeType to look at the UseTypoMetrics bit. This would allow for the (eventual) simplification of the Skia code. Le mer. 30 janv. 2019 à 20:21, Nikolaus Waxweiler <[email protected]> a écrit : > The short version is that Firefox and Chromium seem to directly access > hhea and typo themselves. The patches seem to have no effect except that > Chromium seems to react to freetype not blindly setting typo values in VF > instances anymore, but only with small metrics changes. > > GTK and Qt let text and UI elements compress if bit 7 is set and typo > ascender plus descender < hhea ascender plus descender. I have no idea how > much this is the result of theming in either toolkit and if it is what is > supposed to happen. > > So. > > Still not sure we want mvar typo deltas to modify currently active metrics? > > ... Merge and break out asbestos pants? > _______________________________________________ > Freetype-devel mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/freetype-devel >
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